width_control->Changed.connect (panvalue_connections, invalidator(*this), boost::bind (&StereoPanner::value_change, this), gui_context());
_panner_shell->Changed.connect (panshell_connections, invalidator (*this), boost::bind (&StereoPanner::bypass_handler, this), gui_context());
width_control->Changed.connect (panvalue_connections, invalidator(*this), boost::bind (&StereoPanner::value_change, this), gui_context());
_panner_shell->Changed.connect (panshell_connections, invalidator (*this), boost::bind (&StereoPanner::bypass_handler, this), gui_context());